org.apache.nutch.db
Class WebDBReader

java.lang.Object
  org.apache.nutch.db.WebDBReader

All Implemented Interfaces:

IWebDBReader

public class WebDBReader

extends Object

implements IWebDBReader

The WebDBReader implements all the read-only parts of accessing our web database. All the writing ones can be found in WebDBWriter.

Author:

Mike Cafarella

Constructor Summary

WebDBReader(NutchFileSystem nfs, File dbDir)
Open a web db reader for the named directory.

Method Summary

void	close() Shutdown
Link[]	getLinks(MD5Hash md5) Grab all the links from the given MD5 hash.
Link[]	getLinks(UTF8 url) Get all the hyperlinks that link TO the indicated URL.
Page	getPage(String url) Get Page from the pagedb with the given URL
Page[]	getPages(MD5Hash md5) Get Pages from the pagedb according to their content hash.
Enumeration	links() Return all the links, by target URL
static void	main(String[] argv) The WebDBReader.main() provides some handy utility methods for looking through the contents of the webdb.
long	numLinks() Return the number of links in our db.
long	numPages() Return the number of pages we're dealing with
boolean	pageExists(MD5Hash md5) Test whether a certain piece of content is in the database, but don't bother returning the Page(s) itself.
Enumeration	pages() Iterate through all the Pages, sorted by URL
Enumeration	pagesByMD5() Iterate through all the Pages, sorted by MD5

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WebDBReader

public WebDBReader(NutchFileSystem nfs,
                   File dbDir)
            throws IOException,
                   FileNotFoundException

Open a web db reader for the named directory.

Method Detail

close

public void close()
           throws IOException

Shutdown

Specified by:

close in interface IWebDBReader

Throws:

IOException

getPage

public Page getPage(String url)
             throws IOException

Get Page from the pagedb with the given URL

Specified by:

getPage in interface IWebDBReader

Throws:

IOException

getPages

public Page[] getPages(MD5Hash md5)
                throws IOException

Get Pages from the pagedb according to their content hash.

Specified by:

getPages in interface IWebDBReader

Throws:

IOException

pageExists

public boolean pageExists(MD5Hash md5)
                   throws IOException

Test whether a certain piece of content is in the database, but don't bother returning the Page(s) itself.

Specified by:

pageExists in interface IWebDBReader

Throws:

IOException

pages

public Enumeration pages()
                  throws IOException

Iterate through all the Pages, sorted by URL

Specified by:

pages in interface IWebDBReader

Throws:

IOException

pagesByMD5

public Enumeration pagesByMD5()
                       throws IOException

Iterate through all the Pages, sorted by MD5

Specified by:

pagesByMD5 in interface IWebDBReader

Throws:

IOException

numPages

public long numPages()

Return the number of pages we're dealing with

Specified by:

numPages in interface IWebDBReader

getLinks

public Link[] getLinks(UTF8 url)
                throws IOException

Get all the hyperlinks that link TO the indicated URL.

Specified by:

getLinks in interface IWebDBReader

Throws:

IOException

getLinks

public Link[] getLinks(MD5Hash md5)
                throws IOException

Grab all the links from the given MD5 hash.

Specified by:

getLinks in interface IWebDBReader

Throws:

IOException

links

public Enumeration links()

Return all the links, by target URL

Specified by:

links in interface IWebDBReader

numLinks

public long numLinks()

Return the number of links in our db.

Specified by:

numLinks in interface IWebDBReader

main

public static void main(String[] argv)
                 throws FileNotFoundException,
                        IOException

The WebDBReader.main() provides some handy utility methods for looking through the contents of the webdb. Hoo-boy!

Throws:

FileNotFoundException

IOException